Hello neighbor: Trump was photographed next to Enrique Peña Nieto, the president of Mexico, with whom he has had a prickly relationship

All the presidents and prime ministers at the Da Nang event played along with the blue silk shirts on Friday, although Putin upstaged Trump by wearing a dress shirt and tie that was visible underneath his traditional 'ao dai.'

Trump, like everyone else, went open-neck casual.

Vietnam President Trần Đại Quang's team chose the garments, a privilege of host countries that dates back to Bill Clinton at the 1993 APEC summit in Seattle.

That year Clinton gave heads of state matching leather bomber jackets, and some actually wore them.

A year later Indonesia picked up the idea, asking participants to wear traditional patterned batik shirts that some in the U.S. compared to 1960s upholstery.

It could have been worse for Trump: George W. Bush chuckled along with the crowd as he posed in a red woven Chilean poncho in 2008 at the APEC arrival ceremony.

And in Australia the year before, outback raincoats were the order of the day.

Archipelago's leader: Indonesia's President Joko Widodo and his wife Iriana meet Vietnam's president and first lady

Could have been worse: In 2004 George W. Bush played along as Chile's leaders asked everyone to wear traditional woven ponchos

Bill Clinton gave presidents and prime ministers bomber jackets like his (pictured) in 1993

Indonesia's revenge: Clinton's jackets gave President Suharto (3rd from left) the idea of asking everyone to wear batik shirts, and the tradition was born

Putin and Barack Obama were the only leaders since Clinton's launch to take a break from the tradition.

Obama told world leaders in Hawaii six years ago that they didn't have to play along.

Days after joking that he might pass out 'flowered shirts and grass skirts,' Obama explained that he 'I got rid of the Hawaiian shirts because I looked at pictures of some of the previous APEC meetings and some of the garb that had appeared previously, and I thought this may be a tradition that we might want to break,'

'I suggested to leaders – we gave them a shirt, and if they wanted to wear the shirt, I promise you it would have been fine. But I didn't hear a lot of complaints about us breaking precedent on that one.'

In 2014 he endured a wine-colored jacket in China that drew comparisons to Captain Jean-Luc Picard's uniform in 'Star Trek: The New Generation.'

The matching-clothes tradition at APEC summits hasn't always worked out for U.S. presidents; in 2014 Barack Obama participated, earning comparisons with Captain Picard from 'Star Trek'

Last year in Peru the APEC leaders wore matching wool shawls, a more subtle choice than in most other years

The White House said as President Trump arrived in Vietnam on Friday that a highly anticipated formal meeting between him and his Russian counterpart would not be on either leader's schedule.

'Regarding a Putin meeting, there was never a meeting confirmed, and there will not be one that takes place due to scheduling conflicts on both sides,' Trump's press secretary Sarah Sanders told reporters aboard Air Force One.

'There is no formal meeting or anything scheduled for them.'

'Now, they’re going to be in the same place,' she allowed. 'Are they going to bump into each other and say hello? Certainly possible and likely.'

'But in terms of a scheduled, formal meeting, there’s not one on the calendar and we don’t anticipate that there will be one,' Sanders said.